Improve multidisk game scanning

[sonninnos]

Description

Because at least with Amiga database the last disk in a multidisk game is the one used for hash matching, thus it gets picked as the playlist entry path, which will never work for actual launching, forcing users to use manual scan instead for these particular cases.

So let's simply use the archive itself as the path just as single disk games if the database entry used for matching contains a hint of being a multidisk game.

This way both archives containing one game (core is getting the whole archive) and archives containing different games (core is getting a specific file from the archive) get scanned as playlist items.

Related Issues

Closes https://github.com/libretro/libretro-database/issues/1387